Pressing apparatus

ABSTRACT

A pressing apparatus for compacting powdered material filled into the die chamber of the apparatus, to compacted bodies, is provided with a filling system comprising a filling shoe which is movable over a surface to the filling opening, and with a grating inside of said shoe free of contact with the walls thereof, the grating being connected by a rigid coupling, and the shoe being connected by a lost motion coupling, to a driving system.

United States Patent Plocher et al.

PRESSING APPARATUS inventors: Werner Plocher, Horb-lhlingen;

Franz Klihl, Herdecke; Karl Mertl; Bernhard Hiittermann, both of Glinde, all of Germany Assignees: Jurid Werke GmbH, Glinde;

Maschinenfabrik Laufler & Butscher, Muhlen, both of Germany Filed: June 3, 1974 Appl. No.: 476,147

Foreign Application Priority Data June 6, 1973 Germany 2328699 US. Cl. r. 425/78; 425/130; 425/258 Int. Cl 330i) 11/02; B30b 15/30 Field of Search 425/78, 79, 130, 256, 257,

July s, 1975 [5 6] References Cited UNITED STATES PATENTS 2,492,297 l2/l949 Lagarde 425/258 3,605,825 9/l97l Hermes 425/78 X Primary ExaminerJ. Howard Flint, Jr. Attorney, Agent, or F irmYoung & Thompson 5 7] ABSTRACT A pressing apparatus for compacting powdered material filled into the die chamber of the apparatus, to compacted bodies, is provided with a filling system comprising a filling shoe which is movable over a surface to the filling opening, and with a grating inside of said shoe free of contact with the walls thereof, the grating being connected by a rigid coupling, and the shoe being connected by a lost motion coupling, to a driving system.

5 Claims, 2 Drawing Figures 1 PRESSING APPARATUS BACKGROUND OF THE INVENTION comprising a charging shoe which can be traversed on a die table of a press.

For the production of sinter compacts for powdermetallurgical purposes use is made of pressing dies charged with materials which are substantially in powder form, and which may consist of metal or metal oxide powders and may possibly also contain fibre materials, such as asbestos, or graphite. The particles of such a mixture have different shapes and sizes and they also differ in density. Frequently the flowability of such powder mixtures is rather poor. For charging a pressing die it is necessary to ensure that the materials are evenly distributed in the charging shoe and after the charging step, also in the die, and that they do not segregate whilst being moved. Besides such powder mixtures have a very pronounced tendency to cake. During the charging operation it is important to prevent such agglomerations or at least to ensure that this tendency does not adversely affect the charging operation.

In conventional arrangements the content of the charging shoe is therefore briefly shaken during the charging operation by a brief to and fro movement of the shoe. The shaking motion may be initiated in dependence upon the position of the shoe or it may be initiated at a prescribed time within the operating cycle.

However, when using such devices it has been found that they fail to prevent segregation or caking of the powder material. Moreover, owing to the shaking motion, some of the powder frequently finds its way on to the die table through the gap between the frame of the charging shoe and the track of the shoe on the table. This causes the charging shoe to be lifted off the table altogether. More particularly, when the powder mixtures are abrasive mixtures components of the press tend to wear and this aggravates the tendency of the powder to escape from the shoe during charging.

SUMMARY OF THE INVENTION It is a main object of the present invention to provide apparatus for charging pressing dies in a manner that will substantially prevent the powder from segregating and from agglomerating into lumps during the charging operation, and that will also stop the powder from excaping on to the die table and the track of the charging shoe.

For achieving these objects the invention consists in providing apparatus in which the charging shoe contains elements resembling gratings disposed inside the shoe and firmly connected to drive means which are coupled to the charging shoe in a manner providing lost motion in the direction of traverse of the shoe. Moreover, the elements resembling gratings may be parts of an integrated grating attached to a holder which passes substantially through the wall of the charging shoe, said holder being itself firmly connected to the drive means. The invention thus enables the powder charge inside the shoe to be vibrated above the die without the charging shoe itself participating in the vibration. The grating inside the charging shoe also ensures that agglomerations do not occur which otherwise usually form when the charging shoe is displaced in conventional arrangmerits. At the same time the grating effectively prevents segregation or at least reduces segregation effects to negligible proportions.

According to the invention the charging shoe is loosely coupled with lost motion in its direction of traverse to a drive means which may be a hydraulic piston or a pushrod operated by an eccentric. On the other hand. the vibrating means inside the charging shoe is rigidly coupled to the same drive mean so that for instance a motion reversal of the drive means results in the charging shoe remaining stationary for a short period. during which the vibrating means inside the shoe can still be moved to and fro. In other words. relative displacement between the charging shoe and the vibrating means in its interior can be generated whenever the shoe stops or reverses its direction of motion.

As the vibrating device is operated only when the charging shoe is stationary, the vibratory motion will not cause powder to work its way to the outside of the shoe on to the charging track. Whereas in prior art ap paratus the charging shoe itself was vibrated and thus transferred its vibration to the contents of the shoe, the arrangement provided by the present invention agitates the entire volume of powder inside the shoe and thus also effectively prevents segregation and the formation of powder lumps. This is particularly important in the case of large area flat dies, as used for instance for pressing compacts for large friction liners, in which case the invention ensures an even distribution of the powder mixture.

Another advantage is that the inertial masses which must be accelerated by the rapid movement are sub stantially smaller in the peroposed arrangement than in apparatus heretofore used because only a light-weight vibrating means is needed to vibrate the powder itself and the heavy charging shoe need not be vibrated.

According to yet another feature of the invention the holder of the grating may consist of two bolts attached to the grating and of a yoke which cross-connects the said bolts and through which a coupling bolt affixed to the charging shoe passes with allround clearance. This coupling bolt provides lost motion in the direction of traverse of the shoe, the length of this lost motion being adjustable by an adjusting nut on the coupling bolt attached to the shoe. This arrangement is a simple device for rigidly coupling the vibrating device, and loosely coupling the charging shoe to a common drive means.

In a preferred embodiment a control bar is firmly attached to the holder and extends parallel to the direction of traverse of the charging shoe. It is provided with slots in the direction of traverse for the reception of fingers or like members adapted to cooperate with switch means in a mounting firmly secured to the die table.

Other aspects and features and advantages of the invention will be understood from the claims and from the following particular description in connection with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of apparatus according to the invention, shown partly in section, and

FIG. 2 is a view in plan of the apparatus according to the invention in FIG. I, likewise partly in section.

DESCRIPTION OF AN EMBODIMENT With reference to the drawings apparatus according to the invention includes a charging shoe which can be traversed on a die table I forming part of a press for the production of sinter compacts. Above the die table I is the upper portion 4 of the press carrying an upper punch 41. The press further comprises a bottom portion 5 underneath the die table, comprising a bottom punch SI and a die opening 52.

The charging shoe 2 is laterally guided on the die table 1 by a charging rail 1]. A seal 2l is provided between the charging shoe and the slideway surface on the top of the table 1. For recharging the shoe from a hopper not shown in the drawing the substantially boxshaped charging shoe 2 contains a filling opening 22 in its top.

In the interior of the charging shoe 2 a vibrator 3 is provided which consists substantially of upended sheet metal strips assembled to form a grating. Clearance is provided between the grating 3 and the inside wall of the charging shoe. Instead of providing a grating composed, as shown, of intersecting sheet metal strips, the purpose contemplated by the invention would also be achieved if the sheet metal strips were disposed like the slats of a louvre extending across the direction of traverse of the shoe and joined together by one rib in the centre and frame members on the outsides.

The charging shoe 2 and the vibrator 3 share a common drive means which in the illustrated embodiment consists of a hydraulic cylinder 6 containing a piston 61. The hydraulic cylinder 6 is secured to the table 1 by brackets 63. The grate-like vibrator 3 is securely attached to the hydraulic drive means, i.e., to the piston 61, by a piston rod 62, an intermediate member 7], a yoke 72, and fixing bolts 73.

The fixing bolts 73 pass with clearance through a wall 23 of the charging shoe 2 facing the drive means. The gap in the wall 23 due to this clearance is sealed by sealing collars 24 which do not substantially hinder the relative vibratory motion between the vibrator 3 and charging shoe 2.

Since the vibrator 3 is movable, i.e., in the illustrated example displaceable inside the charging shoe 2 in the direction of traverse of the shoe, the vibrator 3, the bolts 73 and the yoke 72 function as means for loosely coupling the charging shoe 2 to the piston 61 of the hydraulic drive of the vibrator 3. The direction of vibration of the vibrator 3 for vibrating the powder contained in the charging shoe 2 is indicated by an arrow in FIG. 1.

For relief of traction forces and for adjusting the amplitude of vibratory motion of the vibrator 3 in the charging shoe 2 during vibration a threaded coupling bolt 25 is secured in the wall 23 of the charging shoe 2. This threaded bolt extends substantially parallel to the bolts 73 and carries an adjusting nut 26 and a lock nut 27. The bolt 25 passes with allround clearance through the yoke 72. The amplitude of displacement of the vibrator 3 inside the charging shoe 2 can now be determined by the distance of the adjusting nut 26 from the head 28 of the bolt 25 on the far side of the yoke 72, a distance which limits the distance the yoke 72 can move on the bolt.

The intermediate member 71 carries a control rod 8 which extends parallel to the direction of traverse of the charging shoe. The control rod 8 contains slots 82 for the reception of adjustable cam or finger members adapted to cooperate with control elements 81 which are mounted on the die table 1.

When the charging shoe 2 is pushed across the die table 1 towards the die 52, the yoke 72 will bear against the adjustable nut 26. At the end of its traverse the charging shoe 2 stops above the die 52, this being controlled by the suitably adjusted cam or finger members on the control bar 8 cooperating with an electric switch 8| controlling an electrically driven hydraulik pump not shown in the drawing and the cylinder 6 containing the double-acting piston 61. As soon as the piston 61 reverses its direction of motion the yoke 72 moves away from the adjustable nut 26 and hence disengages the charging shoe from its drive means. For effecting the reciprocating vibratory motion of the vibrator 3, i.e., for effecting the vibrating operation, there is now available an amplitude of reciprocation which is at most equal to the difference between the length of the vibrator 3 in the direction of traverse of the charging shoe and the inside length measured in the same direction of the charging shoe, and which is adjustable within these limits by the present distance between the nut 26 and the bolt head 28. The vibration is controlled by appropriate finger members on the control bar 8.

In the illustrated preferred embodiment of the invention the sheet metal strips forming the grating are assembled and joined to create a lozenge pattern in the direction of reciprocation. During vibration all the components of the grating will therefore act on the powder inside the shoe.

It should further be emphasized that the passage of the parts 73 through the wall 23 and of the coupling bolt 25 through yoke 72 with allround clearance is understood to mean that there is no significant impairment of the freedom of relative movement of the two parts 2 and 3. Within the ambit of this definition any arrangement which ensures sufficiently low friction relative movement is considered to be embraced by the term allround clearance.

What we claim is:

l. A pressing apparatus for compacting powdered material into compacted bodies comprising a table having a table surface,

a die chamber within said table and having a filling opening bordered by parts of said table surface, compacting means cooperating with said die chamher for compacting the contents thereof,

a frame having wall means which are provided with lower and upper edges and which enclose an interior space, said upper edges defining a top opening for receiving powdered material, and said lower edges which are in substantially close and complete contact with said table surface, defining a bottom opening for the discharge of said powdered material,

grating means in said interior space free of contact with said wall means,

driving means for reciprocatingly moving said frame on the table surface from a first receiving position to a second discharge position on top of the filling opening and back, and for oscillatory motion of said grating means,

rigid coupling means between said grating means and said driving means,

and lost motion coupling means between said frame and said driving means.

2. A pressing apparatus according to claim I wherein said grating means is in rigid connection with bracket means having at least one shaft, and said wall means is provided with at least one opening through which said shaft extends free of contact with said wall means, the end of said shaft outside of said frame being rigidly coupled to said driving means.

3. A pressing apparatus according to claim 2 wherein said frame is provided with an extension which is lor cated adjacent to said shaft and wherein cooperating stop means are provided on said extension and said shaft for limiting the relative motion of said grating means and said frame.

4. A pressing apparatus according to claim 1 wherein opening. 

1. A pressing apparatus for compacting powdered material into compacted bodies comprising a table having a table surface, a die chamber within said table and having a filling opening bordered by parts of said table surface, compacting means cooperating with said die chamber for compacting the contents thereof, a frame having wall means which are provided with lower and upper edges and which enclose an interior space, said upper edges defining a top opening for receiving powdered material, and said lower edges which are in substantially close and complete contact with said table surface, defining a bottom opening for the discharge of said powdered material, grating means in said interior space free of contact with said wall means, driving means for reciprocatingly moving said frame on the table surface from a first receiving position to a second discharge position on top of the filling opening and back, and for oscillatory motion of said grating means, rigid coupling means between said grating means and said driving means, and lost motion coupling means between said frame and said driving means.
 2. A pressing apparatus according to claim 1 wherein said grating means is in rigid connection with bracket means having at least one shaft, and said wall means is provided with at least one opening through which said shaft extends free of contact with said wall means, the end of said shaft outside of said frame being rigidly coupled to said driving means.
 3. A pressing apparatus according to claim 2 wherein said frame is provided with an extension which is located adjacent to said shaft and wherein cooperating stop means are provided on said extension and said shaft for limiting the relative motion of said grating means and said frame.
 4. A pressing apparatus according to claim 1 wherein said wall means are provided with an opening and said grating means are in rigid connection with an extension extending contact free through said opening to the outside of said frame said extension carrying control means which are in cooperation with switch means controlling the operation of said driving means.
 5. A pressing device according to claim 2 wherein resilient ceiling means are provided at said at least one opening. 